A typical wireless communication device, such as a mobile phone, comprises, among other things, a processor coupled to a memory and to a transceiver, each enclosed in a housing. A mobile power source, such as a battery, is coupled to and supplies power to the processor, the memory and the transceiver. A speaker and a microphone are also enclosed within the housing for transmitting and receiving, respectively, acoustic signals to and from a user of the wireless communication device. The wireless communication device communicates information by transmitting and receiving electromagnetic (“EM”) energy in the radio frequency (“RF”) band via an antenna coupled to the transceiver.
More recently, mobile communication devices have been developed that communicate over a plurality of air interface technologies. For example, a mobile handset may be designed to incorporate both cellular telephony technology and wireless local area network (“WLAN”) technology. Such devices can be referred to as multi-mode handset devices, because of the multiple air interface modes in which the device may be configured.
A significant challenge facing the design and development of multi-mode devices is the ability to efficiently detect the presence of the networks associated with the various air interface technologies, particularly WLAN networks. The main reason for this difficulty is the fact that WLAN coverage is small and spotty (i.e., extremely limited geographically) compared to cellular network coverage, which is ubiquitous. Since the overall WLAN coverage within the cellular coverage region is comparatively small, the multi-mode device does not typically encounter a WLAN network when traveling. Because searching for WLAN services consumes a significant amount of power, the present technique requiring continuous searches for WLAN networks results in disadvantageously depleting the limited and precious mobile power source of multi-mode devices.
Other implementations provide for a fixed search time period in which to acquire WLAN services. A fixed setting (unchangeable to the user) is commonly implemented in mobile wireless communication devices in order to allow the network carrier to control the functionality and features of the device. This limitation is particularly true of system related functions, such as system searching, so that the device will have predictability in behavior. Having a fixed search time period helps conserve power, but has its own disadvantages. For example, in some cases the device will search longer than necessary and unnecessarily consume mobile power resources, as noted above. Yet in other situations, the search for WLAN service may terminate too early, thereby failing to acquire WLAN service within close proximity.
Accordingly, there is a strong need in the art for an efficient and optimized method for providing system searching or scanning for multi-mode wireless communication devices.